Abstract: A prosthetic vertebra has a first hollow parallelepiped-shaped component and a second component shaped identically to the first component and marginally smaller than the first component. The second component can accordingly be positioned partially within the first component and can be axially moved within the first component, so that the overall length of the prosthetic vertebra can be established by appropriately moving the second component within the first. A set screw is threadably engageable with the first component and can be tightened against the second component to hold the components axially stationary relative to each other, once the prosthetic vertebra has been positioned in the patient and its length adjusted as appropriate to fit the patient.